For connections being exposed to large and continuous variations of force, it is known to provide the force-adsorbing components with a pre-tension in order to prevent play and resulting fatigue during such force variations. In the art there is a plurality of solutions for obtaining a predetermined pre-tension. One way is to simply tighten a nut on an elongated bolt with a certain torque, resulting in the bolt being tensioned with a certain force.
Other solutions involve moving inclined faces against each other along a predetermined distance, thereby stretching force-adsorbing components to which one of the faces is functionally connected a predetermined distance. One such solution is described in international patent application publication WO 2010069863. Here, the inclined faces are first made to abut each other, and then they are moved, sliding against each other along a predetermined distance. This results in a predetermined pre-tension in a connection sleeve carrying one of the inclined surfaces. A similar solution is described in WO03002845.
Furthermore, it is known to connect to tubular members, either within bores or externally, by means of locking elements that are moved in a radial direction by actuation of an actuation member. International patent application publication WO 2010081621 describes a connector assembly which is suited to connect to the external or internal locking profiles of a tubular element. This solution exhibits a plurality of locking elements which are moved radially into and out of a locking engagement by means of an activation sleeve engaging the locking elements.
Patent application publication US 20050146137 describes a connector with pivoting fingers that engages the flanges of two oppositely pipe ends. By appropriate selection of the radial size of a pre-tension ring (22) the operator may choose a predetermined amount of pretension in the fingers.
Another patent application publication, US 2005001427, describes another connector assembly where a plurality of collet fingers that engage a profile at each end of a pipe section. The collet fingers are forced into engagement with a threaded outer sleeve that is slid over the fingers and with an inclined face forces the collets into said profiles.
Publication U.S. Pat. No. 4,708,376 describes a hydraulic collet type connector adapted to lock onto a wellhead. A plurality of pivoting collet segments are arranged about the periphery of an upper body and adapted to connect to a locking groove in the wellhead.